Bump about_libraries from 8.1.4 to 8.1.6 (#861)

Bumps `about_libraries` from 8.1.4 to 8.1.6.

Updates `aboutlibraries-plugin` from 8.1.4 to 8.1.6
- [Release notes](https://github.com/mikepenz/AboutLibraries/releases)
- [Changelog](https://github.com/mikepenz/AboutLibraries/blob/develop/gradle-release.gradle)
- [Commits](https://github.com/mikepenz/AboutLibraries/compare/v8.1.4...v8.1.6)

Updates `aboutlibraries-core` from 8.1.4 to 8.1.6
- [Release notes](https://github.com/mikepenz/AboutLibraries/releases)
- [Changelog](https://github.com/mikepenz/AboutLibraries/blob/develop/gradle-release.gradle)
- [Commits](https://github.com/mikepenz/AboutLibraries/compare/v8.1.4...v8.1.6)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build.gradle

@@ -1,6 +1,6 @@
 buildscript {
     ext.kotlin_version = '1.3.72'
-    ext.about_libraries = '8.1.4'
+    ext.about_libraries = '8.1.6'
     repositories {
         mavenCentral()
         google()